This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. Conventional T1 and T2 imaging techniques are useful for observing late structural morphological changes to the cartilage within the femoral-tibial joint but are insensitive to early biochemical changes. T1[unreadable] MRI has shown promise as a diagnostic measure of early osteoarthritis. The T1[unreadable] relaxation time constant is sensitivity to the interaction between bulk water molecules and extracellular matrix macromolecules such as the proteoglycans in articular cartilage. In this study, we evaluate the efficacy of T1[unreadable] MRI to characterize osteoarthritis changes in an animal model (Dunkin-Hartley guinea pig) of spontaneous osteoarthritis formation.